Electrical connector



April 13, 1948. H, H, wERMlNE 2,439,767

l ELECTRICAL CONNECTOR d Filed March 20, 1945 3 Sheets-Sheet 1 'Ill' ---i f 7 r r r lv 7 @5.1.2. J

April 13, 1948n H. H. wERMlNL-z ELECTRICAL CONNECTOR V 3 Sheets-Sheet 2 Filed 'March 20. 1943 H. H. WERMINE ELEcTRIcAL CONNECTOR April 13, 1948.

Filed March 20, 1945 3 Sheets-Sheet 3 Patented Apr. 13, 1948 ELECTRICAL CONNECTOR Hugo H. Wermlne, Wheaton, Ill., asslgnor to Belden Manufacturing Company, a corporation of Illinois Applicationl March 20, 1943, Serial No. 479,846

' 10 Claims.

. n 1 The present invention relatesgenerally to electrical connector plugs of the type used for connecting appliance cords or the like' to a source of electrical power, and it has particular relation to the blade tenninals which form a part of such devices. This application is a continuation in part of my prior application Ser. No. 375,870, which was filed on January 25, 1941, now abandoned, and which is assigned to the assignee of this invention. A

The usual electrical connector plug of the subject type comprises a body of insulating material, h-aving a central aperture for receiving the conductor cord, and two or more blade terminals for the cord conductors. The terminals are supported upon., and project outwardly from, the insulating body and are adapted to engage the contacts of the receptacle or other power outlet with which the plug is to be used. For safety reasons, it is desirable that the plug body shall be made oi a soft, unbreakable material such as a resilient rubber compound, although a large number of the connector plugs in use are of the so-called hard body or breakable type.

Considerable difficulty has been experienced in the past in providing good electrical contact between the' blade terminals of connector plugs and the cooperating contacts of receptaclesy or other power outlets, particularly in the case of receptacles which have been in use for some time. To overcome this difculty, it has been proposed to use spring lblades -as the plug terminals, but despite considerable work along this line and the development of a substantial number of devices no completely satisfactory spring blade has been developed.

The principal object of the present invention, therefor, is to provide an improved spring blade for electrical connector plugs, and the like, which shall assure good electrical contact with the contacts of standard receptacles or other power outlets regardless of wearing or loss of resilience in those contacts, and which shall be free from the other objections of the prior devices.

As will hereinafter appear, this object is accomplished by the provision of a transversely resilient, two-ply blade of novel structural arrangement and design, the shape of the blade being such that it not only accomplishes improved electrical contact with the contacts of standard receptacles but, in addition, it provides a mechanical connection between the associated plug body and the receptacle. This mechanical connection between the plug body and the receptacle is a sub,- stantial departure from the teachings of the prior art, and is an important feature of my invention, for the reason that it prevents overstressing both of the terminal blades and of the cooperating receptacle contacts. The spring blades of the present invention may be used in connection with either hard or soft body plugs.

It is also an object of my invention to provide an improved spring blade whichshall include means -for anchoring the blade in place in the supporting body with which it is used, andto provide an improved spring blade in accorddance with the aforementioned objects which can be manufactured at low cost by the use -oi conventional metal working equipment.

Other objects and the various advantages of the invention will be made apparent by reference to the accompanying drawings and the following description of certain preferred embodiments thereof.

In the drawings:

Fig. lis a perspective view, partially in section, of a, soft body, connector plug provided with spring blades constructed in accordance with the present invention;

Fig. 2 is a Vertical sectional view of the connector plug shown in Fig. 1; t

Fig.V 3 is a sectional View showing the manner in which the plug illustrated in Figs. l and 2 is inserted into a receptacle, the blades being illustratedin elevation and pushed about two-thirds of thevway into the receptacle in this View;

Fig. 4 is a view similar to Fig. 3 showing the plug in its normal operating position with the blades completely seated in the receptacle, the blades being illustrated in section iny this view;

Figs. 5 and 6 are elevational views partly in I section showing the manner in which the spring blades of the present invention coact with various types of standard outlet receptacles;

Fig. 7 is an elevational view of one of the blades forming a part of the connector plugs illustrated in Figs. 1 to 4;

Figs. 8 and 9 are enlarged sectional views on the lines 8--8 and 9-9, respectively, of Fig. 7;

Fig. 10 is a perspective view, similar to Fig. 1, showing a modified form of the invention;

Fig. 11 is a vertical Vsectional view of the plug illustrated in Fig. 10, one of the blades being illustrated in section and the other in elevation;

Fig. `12 is an elevational view of one of the i blades forming a part' of the plug illustrated in Figs. 10 and 11;

Fig. 13 is a vertical section of the blade illustrated in Fig. 12;

amava? Fline H-M of Fig. 13;

Figs. 15 and 16 are, respectively, front and side elevational views of a second modified blade construction embodyingcertain of the features of the present invention;

Fig. 17 is a vertical sectional' view of the blade illustrated in Figs. 15 and 16;

Fig. 18 is an enlarged sectional view on the line |8|3 of Fig. 17; y A

Figs. 19 and 20 are,l respectively. iront and side elevational views of another blade construction in accordance with the present invention;

Fig. 21 is a side elevational'vlew of a slightly modliied form of the blade construction illustrated in Figs. 19 and 20 Figs. 22 and 23 are. respectively, enlarged sectional views on the lines 22-22 and 23-23 of Figs. and 21 Fig. 24 is a vertical sectional View similar to Fig. 2 of a plug equipped with spring blades of the types shown in Figs. 19 to 23;

Fig. 25 is a front elevational view of another spring blade construction embodying certain of the features of the present invention;

Fig. 26 is a sectional view on` the line 26-26 of Fig. 25; and y;

Figs. 27 and 28 are, respectively, front and side elevational views of still another spring blade construction embodying certain of the features of the present, invention.

The connector plugs illustrated in the drawings are of the soft body, two conductor type, and are similar in construction to the connector plugs illustratedin my earlier Patent 1,858,196. These plugs include a main body part 3| which is preferably molded of a resilient, rubber or equivalent compound. The main body part 3| is provided with a centrally disposed passageway 33 for receiving a connector cord 35, which in the structures illustrated is of the duplex type, and with two suitably positioned recesses 3l for receiving and tightly engaging the inner orshankvend of the two terminal blades. In the construction shown in Figs. 1 to 4, the recesses are enlarged at the inner portion thereof so as to provide an abutment 38 which, as will hereinafter appear, ooacts with the blades to lock them in place.

The upper portion of the central passageway 33 is enlarged to receive a secondary body part or retainer 39 which serves to hold the blades in spaced relationship and to aid in supporting them in the main body part 3|. In order to hold together the plug parts without the use of screw or other fastening means, in accordance with the disclosure of Patent 1,858,196, the walls of the main or outer body part 3| are provided with tWO diametl'ially Opposite, under-Cut portions 4| (see Figs. 1 and 10) which engag projecting edge portions 43 of the secondary or inner body part 39 when the plug is assembled. 'I'he plug parts are thus held together by the resilience of either or both of the body parts, and the plugs can be assembled only by virtue of the fact that at least one of the body parts is made of resilient material. Each of the conductor cords 35 includes two, separate, insulated wires or cables 45, and the end of one of the metallic conductors forming a part of each oi the wires 45 is solderedor otherwise attached to one of the blades as illustrated at 41. The outer body part 3| is recessed as illustrated at 49 to receive the solder or other connecting means.

During the assembling of connector plugs of the general type illustrated in the drawings, the

outer body part 3| is slipped over the end of the connector cord with which the plug is to be used, and the connector blades are soldered in place on the bai-ed ends ot the cord conductors. The outer body part 3| and the cord are then placed in the stationary element of an assembly press. The movable element of this press is adapted to hold the blades in parallel relationship with one of the inner body parts 39 in place therebetween. On operation of the press, the blades are automatically pressed into and seated in the blade 33 is forced into place so as to lock with the outer 'body part 3| as shown. The plugs may be assembled by hand in a. similar manner.

As stated previously. the present invention is concerned primarily with the terminal contacts or blades, and, as will hereinafter appear, the spring blades of my invention can be used in connection with resilient or soft body plugs, such as have been described above, or in connection with hard body plugs. In view of the fact that all power outlet receptacles are made to certain standard dimensions, blades for use with electrical plug connectors must conform to standard dimensional requirements, and this requirement seriously complicates the problem of providing a satisfactory spring blade, particularly since these dimension requirements were decided upon long before'the need for spring blades arose.

The `standard specications in use in the United States at the present time are those of the Underwriters Laboratory, which is sponsored by the National Board of Fire Underwriters. The

specications of the Underwriters Laboratory provide that the blade shall project from the plug body not less than .625 inch and not more than .718 inch, and that if the blade be provided with a hole adjacent its outer end, such hole shall have an inside diameter of .056 to .125 inch and shall be located so that the outermost edge of the hole is .542 inch, with certain allowable tolerances, from the face of the plug body. The term face of the plug body is applied to the plane of contact between the plug and the cooperating receptacle, and is used in this sense herein. The Underwriters speciications further provide that the width of the blade shall bev .250 inch, that the incompressible thickness of the blade shall be not more than .060 inch, or approximately 11g of an inch, and that the center lines of the blades in the completed plug shall be spaced apart exactly .50 inch.

The Underwriters specifications include similar provision for the receptacles with which the plugs are used. While the receptacle specifications permit of somewhat greater variation than the plug specications, they do provide for a blade receiving opening in the receptacle having a minimum thickness within the range of approximately 11s to sa; of an inch, and a spacing on the center lines of the receptacle openings of exactly one-half inch, the spacing of the socket openings thus coinciding with the standard spacing of the blades. The shape of the insulating body part of so-called "standard receptacles varies quite substantially. The receptacle body parts 5| and 53 of Figs. 5 and 6 are illustrative of two extreme types, the body part 5I of Fig. 5 having a. body which is ush with the plug face, and the body part 53 of Fig. 6 being of the deeply recessed type. A more common type is illustrated at 55 in Figs. 3 and 4.

The improved spring blade of the present invention constitutes a two-ply, transversely resilient blade which, in its physical dimensions, fully conforms to the above stated requirements f the Underwriters Laboratory. The blade is manufactured by folding over and shaping a strip of suitable spring material of standard prong t width (.25 in.) so as to provide two longitudinally spaced, transversely resilient contact portions, A and B, and a shank or support portion S, which may take various forms.

The, outermost contact portion A comprises co-extensive, substantially parallel sections 51 of the strip which are spaced apart a distance which should not exceed about one-fourth the width W of the strip and which have a length within the approximate range of W to three halves W. In certain instances, it has been found desirable to provide a slight taper of the order of about 2 to 5 degrees to the two half sections 5l of the contact portion A, the taper being in such direction as to provide the minimum .blade width at the. outer extremity of the blade. Hence, the term substantially parallel" as used herein is intended to include constructions which may be slightly tapering, or which are truly parallel.

The inner contact portion B has a length approximately equal to three halves the width W of the strip, and comprises symmetrical, outwardly bowed, arcuate sections 59 of the strip, the radius of the defining surfaces of said arcuate sections 59 being approximately equal to twice the widthy W of the strip.

The strip material from which the blades are manufactured is preferably spring brass or Phosphor bronze, and tests indicate that it should have a thickness within the range of approximately .015 to .030 inch. Spring brass (such as commercially available Scoville alloy 23) having a thickness of .020 inch is particularly satisfactory. The two halves of the strip are bent back on each other along a smooth radius. When a spring brass material having a thickness of .020 inch is used this radius should be not less than about one-half the thickness of the strip. The two halves of the blade are symmetrically disposed with reference to the longitudinal axis of the blade, and the relative dimensions of the plug body and the shank portion S should be such that the inner or shank end of the bowed contact portion B normally will be spaced outwardly from the face of the plug body a distance about equal to once or twice the thickness of the strip of material from which the blade prong is made.

The proportions of the contact portions of the blades are such that the mid-point of the bowed contact portion B and the center lines of the defining arcuate surfaces for the two body sections 59 making up`the contact portion B are spaced from the face of the plug body a distance approximately equal to ory slightly less than the width \W of the strip. This dimension is considered quite important in that it-locates the widest part of the contact portion B so as to assure the obtaining of a good mechanical connection with the receptacle body. This will be described in greater detail in a subsequent para-v graph. The blade should have a maximum transverse width in the body contact portion B, the dimension C in the drawings, approxiinatell equal to one-half the width W of the strip from which the blade is made. i

Particularly satisfactory results are obtained when the shank portion S of the spring blade of the present invention is provided with a longitudinally extending stiifening rib, as illustrated at 6| in the embodiment of Figs. 1 to 9. The

advantageous results. For example, if the stiifenf ing rib is terminated short of the bowed contact portion B, a distance equal to about one-half of the width W of the strip, as illustrated at 63 in the embodiment of Figs. 27 and 28, there will be provided an auxiliary, straight, parallel sided, spring portion D` adjacent the bowed contact portion B which will extend into the plug body for some distance.

The shank stiifening ribs are most conveniently formed by a rolling, stamping, or other embossing operation. and give good results when of a depth approximately equal to one-half the thicknes of the stripmaterial from which the blade is made. The stiilening ribs are preferably located centrally of the prong shanks. and a width of approximately one-half the width of the blade is satisfactory in most instances. In the different embodiments of the invention illustrated in the drawings, the stiffening ribs are of different lengths to accomplish certain different desired results.

In the construction illustrated in Figs. 1 to 9 inclusive, the ribs 6l terminate short of the lower ends of the two halves 'B5 and 6l of the blade shank S, and the lower end 69 of the inner half section 6l of the shank is folded over as illustrated particularly in Fig. 9. This folded over end 69 serves to hold the two half sections .of the shank portion of the blade in contact with each other, and it is also used as a means for locking the blades in the blade supporting recesses 3l formed in the plug body. To facilitate the accomplishing of this locking function, the folded over end portion 69 should project outwardly from the plane of the blade; an angle of the order of 12 degrees as shown at M in Fig. 9 will usually function satisfactorily. This outwardly projecting, integral portion of the blade formed by the folded over end b9 is adapted to abut againstthe upper dening wall 38 of the blade receiving recess 3l formed in the outer body part 3l, and thereby provides a highly eilective means for locking the blades against longitudinal movement with reference to the plug body in which they are supported. The projection 13 which results from the termination of the rib 6i in the shank portion 65 short of the end thereof provides a spring abutment against which the folded over portion 69 of the other half 6l of the shank may rest. This is of value in facilitating the assembling of the device and in maintaining the folded over locking portion 69 in position.

The stiifening rib may be omitted in either or both of the shank sections. Invsuch instances the half sections of the shank will be plain, as illustrated particularly in Fig. 25. These plain shank constructions are somewhat less satisfactory than the constructions which include a stiffening rib or ribs in one or both of the shank sections. v

To provide an interlocking engagement with the stationary contacts 15 of the usual standard receptacles, such as are illustrated in Figs. 3 to 6, the two blade sections 5l which define the parallel sided contact portion A are preferably provided with opposed .holes Il which engage the usual projections i9 constituting a part oi the receptacle contacts 1 5. The holes 'l1 may be formed by a straight punching operation, or

by a combined punching and embossing operation. The holes 'i1 shown in the embodiment of the invention illustrated in Figs. 1 to 9 and also in the embodiments illustrated in Figs. 10 to 18 and 25 to 28 are of the straight punched type. Examples of the embossed type are illustrated at 8l, in Figs. 19 to 24.

Aligning holes 83 are also punched or otherwise formed in the two half sections 65 and 61 of the blade shank tir receiving the cord ccnv ductors so as to facilitate the soldering of the cord conductors to the blades. If desired, the holes 83 may be threaded as indicated in Figs. 27 and 28 for the reception of screw fastening means in place of the soldered connection 41 illustrated in the other figures of the drawing. The soldered connection 4l serves as an additional means for mechanically connecting the shank sections 65 and 6l' of the blade construction illustrated in Figs. 1 through 9, and thereby stiiens the shank'to some extent. In certain of the other illustrated embodiments of the invention, as for example, the construction illustrated in Figs. 19 through 26, the soldered connection fl'i is relied upon as the principal means for fastening together the two half sections of the prong shank.

The improved operation of the spring blades of the present invention is illustrated particularly in Figs. 3, 4, 5, and 6. As shown in Fig. 3, the hat sided contact portion A and the curved outer end of the blades facilitates the entry of the blades into the blade receiving openings 85 in the insulating body 55 of the receptacle, and aid in effecting smooth operation of the bowed contact portions B as the plug is pushed into the receptacle. if the receptacle is of average construction and is provided with blade receiving openings 85 recessed about the average distance below the face of the receptacle, as illustrated in Figs. 3 and 5, by the time the blades are fully seated in the receptaclefthe bowed contact portions B will have expanded so as to engage the inner edges of the sides of the blade receiving openings in the receptacle body as shown in Fig. 4. The plug and the blades will thereby be urged into the receptacle body. At the same time, each of the flat sided contact portions A, by virtue of the resilience of those portions of the blade and also by virtue of the resilient action of the bowed portions B, will engage and be held in rm contact with the cooperating receptacle contacts 15.

The net result is two-fold. By virtue of the engagement of the bowed contact portions B with the body 55 of the'receptacle, the connector plug is mechanically connected to the receptacle body, while inside the receptacle a positive pressure electrical contact is assured. The mechanical connecting of the blade to the receptacle body prevents wobbling of the plug with the usual accompanying injury to the receptacle contacts, and the balanced spring action of the contact portions of the blades not only assures that the blades remain parallel as they are moved into and out of the receptacle, .but in addition, assures positive electrical contact between the blades and the receptacle contacts when the blades are within the receptacle.

These advantages of mechanical connection between the plug body and the receptacle body and an improved spring pressure contact between the blades of the plug and the receptacle contacts are obtained with practically all of the standard receptacles now on the market. If the receptacle body is of the flush ty! e, such as is shown in Fig. 5, the mechanical connection is than is the case with the usual receptacle construction illustrated in Figs. 3 and 4.

In the extreme case of a receptacle body having very deeply recessed openings 85 for the plug contacts as illustrated in Fig. 6, the mechanical connection is attained adjacent or just below the mid-point of the bowed section B of the blade contacts. In this instance. the increased compression of the bowed contact portions B compensates for the somewhat lessened mechanical advantage of the connection and assures a positive mechanical inter-connecting of the receptacle body and the blade terminals of the plugs. The receptacle structures illustrated in Figs. 5 and 6 are extreme cases, but even in these 1nstances it will be seen that the important advantages of the blade construction of the present invention are completely realized. None of the prior art arrangements has produced nearly as satisfactory operation as this.

While the embodiment of the invention just described has particular advantages, there are other possible blade constructions embodying the disclosed principles which will be found particularly useful under certain conditions. For example, in the small, nat-body plugs of the type illustrated in Figs. 10 and 11, the walls of the 'outer body part 3i are somewhat thinner and somewhat more exible than is the case in the round type of plug illustrated in Figs. 1 and 2, and it is considered inadvisable to locate the blade locking means adjacent the base of the blade receiving recesses 3l in these plugs. Hence, the shank portions S of the prong construction shown in Figs. 12 to 18 are designed with a view to locking with an abutment 8l provided internally of the plug body by suitable extension of the recess 49 which serves the additional function of providing space for the soldered connection il used in connecting the cord conductors to the prongs. The contact portions A and B of the blades illustrated in these :figures of the drawings are substantially identical in form and dimensions with the construction previously described, and the blades are manufactured in a similar manner by -folding over and shaping a strip of suitable spring material of standard width.

In the particular prong construction shown in Figs. 10 to 14, the two half sections 89 and 9| of the shank portion S are provided with embossed ribs 93 which extend downwardly from the bowed contact portion B about one-third the length of the shank, the remainder of the half sections of the shank being flat. The end 95 of the outer shank section 9| is folded back upon itself as shown, to provide an integral, outwardly projecting latching portion 91. Suitable aligning openings 99 are punched throughv the two shank portions 89 and 9i and the folded over end in order to receive the associated cord conductor which, in the assembled plug, will be -soldered in place as shown particularly by the soldered connection 4l -in Figs.- 10 and 1l. The soldered connection 41 also serves to mechanically connect the two half sections 89 and 9i of the shank portion and the folded over end 85,

9 are assembled in exactly the same manner as the blade construction previously described.

The blade construction shown in Figs. 15 to 18 is somewhat similar to the blade construction shown in Figs. 12 to 14, and is likewise particularly adapted for use in connection with the small, nat-sided, soft body plugs, although it is capable of use in connection with plug bodies of other types. The blade construction of Figs. 15

,to 18 is likewise manufactured from a single,

folded over strip of spring brass or other suitable material, and it includes an outer contact portion A and a second contact portion B, both of which are similar in form and dimensions to the contact portions A and B ofthe previously described constructions.

The shank portion S of this blade construction includes two cooperating sections I| and |03 each of which is provided with a longitudinal extending, centrally disposed, stiiening rib |05. The ribs have a width about equal to about one-half the width of the blade. The lower end of the inner shank section |0| is folded back as illustrated at |01, and the lower end of the outer shank section |03 is bent so as to provide an integral, outwardly extending projection |09 which is generally similar in function to the projection 91 of the construction previously described. Aligning holes I are punched in the folded over portion sections |0| and |01 to provide an opening for receiving the cord conductor to which the prong is attached in use.

The blade constructions illustrated in Figs. 19 to 28 are substantially identical with the blade constructions shown in my prior application, Ser.

No. 375,870 of which this application is a Cantin-- nation in part. In all of these constructions the blade is manufactured by folding over a strip of suitable material, such as spring brass, to provide two longitudinally spaced, transversely resilient, contact portions A and B which are substantially identical in shape and dimensions with the contact portions A and B of the previously described embodiments.

The shank portion S of the construction shown in Figs. 19, 20, and 22, is dened by two, parallel sections ||3 of the strip from which the blade is manufactured. The shank sections |13 extend side by side in contact with each other, and particularly satisfactory results are obtained if the two shank portions I|3 are provided with longitudinally extending stiiening ribs ||5, as illustrated. The ribs |15 are conveniently formed, as in the previously described embodiments, by a rolling, stamping or embossing operation, and they may be of any convenient depth, although a depth of about one-half the thickness of the blade is particularly recommended. The ribs I I5 should be centrally located and appear to give the best results with a width of approximately onehalf the width of the blade. The rib ||5 may be omitted in one or both of the shank sections ||3 in which case that section of the shank will have the same appearance as the blade illustrated in Fig. 25. Aligned punched holes |I9 are provided for reception of the associated conductor which may conveniently be soldered in place by a soldered connection d1, shown in Fig. 24. The soldered connection 41 serves the further function of mechanically joining together the two 'shank portions of the blade.

When using blades of the general type shown in Figs. 19, 20, and 22, there will be in some instances sufficient friction between the blades and the cooperating body parts of the plug to hold the 10 blades against lengthwise movement relative to the body when the plug is pushed into or with` drawn from the receptacle. However, as previously pointed out, positive interlocking of the blades with the plug body is sometimes desirable, and this blade construction can be readily changed to a locking type blade by the provision of a pressed out portion ||1, as illustrated in Figs. 21

and 23, or other integral projection for engaging the plug body so as to anchor the blade therein. The pressed out portion ||1 may conveniently constitute metal removed from one of the shank portions ||3 to provide the conductor receiving hole H9.

In the specific construction illustrated, the

pressed out portion ||1 will engage the underside of the inner body part 39 as shown at the right hand side of Fig. 24. The other blade of the plug illustrated in Fig. 24 is of the same construction as the blade of Figs. 19, 20 and 22. It will be understood that under normal practice. both blades will be alike, and differing constructions have been illustrated in this single figure solely to simplify the drawings.

' 'I'he blade construction illustrated in Figs. 25 and 26 is, as has been previously described, simi' lar to the blade constructions of Figs. 19, 20, and 21 except that the shank portions H3 of the blade are not provided with a rib. This blade construction may advantageously include the integral locking projection II'I as shown particularly in Fig. 26.

The blade construction illustrated inFigs. 27 and'28 includes contact portionsA and B, similar to the previously described embodiments. and also a spring portion D which, as previously described, is provided by terminating the stiifening ribs 63 short of the contact portion B. This construction further differs from the .other embodiments of the invention in that the lower` half of the shank section I2| is cut off so as to produce @a shank portion which is in part of single ply construction. This is of value in certain instances, particularly where it is desired to save metal.

It will be apparent to those skilled in the art that various blade constructions embodying the principles described above may be devised. For this reason, it is my desire that the accompanying claims shall be accorded the broadest possible construction consistent with the language appearing therein and the prior art.

I claim:

1. A two ply, spring blade for electrical plug connectors and thelike, comprising a fiat, metal strip of standard blade width which is folded upon itself at the outer end of said blade and shaped to provide a attened, transversely resilient, contact portion, a bowed, transversely resilient, contact portion, and a shank portion; said flattened contact portion being located at the outer end of said blade, comprising, coextensive, substantially parallel sections of said strip, which are spaced a short distance from each other, and having a length at least approximately equal to the width of said strip; said bowed contact portion being located longitudinally adjacent said flattened contact portion, having a length approximately one and onehalf times the width of said strip, and comprising symmetrically opposed, outwardly bowed sections of said strip; said shank portion comprising coextensive, parallel sections of said strip which contact each other, and at least one of the par- -allel portions of said strip which constitute said acsavev f 11 shank portion being provided with an embossed stiening rib which extends-longitudinally therealong for a substantial distance.

2. A two ply, spring blade for electrical plug connectors and the like comprising a flat, metal strip of uniform width which is folded upon itself at the outer end of said blade and is shaped to provide a flattened, transversely resilient,

' first contact portion, a bowed, transversely resilient, second contact portion, and a shank portion; said flattened contact portion being located at the outer end of said blade, comprising co-extensive, substantially parallel sections of said strip which are spaced apart a distance equal to about one-fourth the width of said strip, and having a length at least approximately equal to the width of said strip; said bowed second contact portion being located longitudinally adjacent said flattened contact portion, having a length approximately one and a half times the width of said strip and comprising symmetrically opposed sections of said strip which are curved along a circular arc, the radius of the defining surfaces of said arcuate curved sections being approximately equal to twice the width of said strip; said shank portion comprising coextensive parallel sections of said strip which contact each other, and at least one of the parallel portions of said strip which constitute said shank portion being provided with an embossed stiffening rib which extends longitudinally therealong for a substantial distance.

3. A two ply, spring blade for electrical plug connectors and the like, comprising a at, metal strip of uniform width which is folded upon itself at the outer end of said blade and shaped to provide two, longitudinally spaced, two ply, transversely resilient contact portions, a transversely resilient spring portion, and a shank portion; o ne of said contact portions being located at the outer end of said blade and comprising coextensive, substantially parallel sections of said strip which are spaced a short distance from each other, the other of said contact portions being located longitudinally adjacent said first mentioned contact portion and comprising coextensive sections of said strip which are spaced apart a substantially greater distance than said parallel sections, whereby said other contact portion has a substantially greater,

- maximum transverse width than said rst mentioned contact portion; said spring portion comprising coextensive, spaced sections of said strip and being located intermediate said other contact portion and said shank portion.

4. A two ply, spring blade for electrical plug connectors andthe like, comprising a flat, metal strip of uniform width which is folded upon itself at the outer end of said Yblade and shaped to provide two transversely resilient, contact portions, a transverse spring portion, and a transversely non-resilient, shank portion; one of said contact portions vbeing located at the outer end of said blade and comprising coeXtensive, spaced, substantially parallel sections of said strip; the

other of said contact portions being located longitudinally adjacent said rst mentioned contact portion and comprising symmetrically opposed, outwardly bowed sections of said strip; vsaid spring portion comprising coextensive, spaced, parallel sections of said strip and being located intermediate said last mentioned contact portion and said shank portion.

5. A two ply, spring blade for electrical plug connectors and the like, comprising a dat, metal strip of uniform width which is folded upon itself at the outer end of said blade and is shaped to provide two, transversely resilient, two ply, contact portions, a transversely resilient, two ply, spring portion, and a transversely non-resilient, shank portion; one of said contact portions being located at the outer end of said blade, and

comprising coextensive, spaced, substantially parallel sections of said strip; the other of said contact portions being located longitudinally adjacent said rst mentioned contact portion and comprising symmetrically opposed, outwardlyy bowed sections of said strip; said spring portion comprising coextensive, spaced, parallel sections of said strip and being located intermediate said last mentioned contact portion and said shank portion; said shank portion comprising parallel sections of said strip which contact each other, and at least one of the parallel sections of said strip which constitute said shank portion being provided with an embossed stiffening rib which extends longitudinally therealong for a substantial distance.

6. A two ply, spring blade for electrical plug connectors and the like, comprising a flat, metal strip of uniform width which is folded upon itself at the outer end of said blade and shaped to provide two, transversely resilient contact portions and a transversely non-resilient shank portion; one of said contact portions being located at the outer end of said blade and comprising coextensive, substantially parallel sections of said strip which are spaced a short distance from each other; the other of said contact portions being located longitudinally adjacent said ilrst mentioned contact portion and comprising coextensive sections of said strip, at least one of which is outwardly bowed so as to cause said other contact portion to have a substantially greater, maximum transverse width than said first mentioned contact portion; said shank portion comprising coextensive parallel sections of said strip and one of said sections being folded over so as to hold together the two parallel sections of said strip and to provide an outwardly extending projection whichis adapted to engage and lock with the body of the plug with which said blade is used.

'7. A two ply, spring blade for electrical plug connectors and the like, comprising a dat, metal strip of standard blade width which is folded upon itself at the outer end of said blade and shaped to provide a flattened, transversely resilient, contact portion, a bowed, transversely resilient, contact portion, and a shank portion; said flattened contact portion being located at the outer end of said blade and comprising coextensive, substantially parallel sections of said strip which are spaced a short distance from each other; said bowed contact portion being located longitudinally adjacent said flattened contact portion and comprising symmetrically opposed, outwardly bowed sections of said strip; said shank portion comprising parallel sections of said strip at least one of 'which is provided with a centrally located longitudinally extending stilfening rib, the end of one of the parallel sections of said strip being folded over the other section so as to mechanically interconnect the two sections of said shank portion and to provide an outwardly extending projection which is adapted to engage the body of the plug with which said blade is used to lock said blade against longitudinal movement relative thereto.

8. A two ply spring blade for electrical plug connectors and the like, comprising a dat metal strip of uniform width which is folded upon itself at the outer end of said blade and shaped to provide two, transversely resilient, contact portions and a transversely non-resilient, shank portion; one of said contact portions being located at the outer end of said bladeand comprising coextensive, substantially parallel sections of said strip which are spaced a short distance from each other; the other of said contact portions being located longitudinally adjacentfsaid iirst mentioned contact portions and comprising coextensive sections of said strip which are spaced apart a substantially greater distance than said parallel sections, whereby said other contact portion has a substantially greater, maximum transverse width than said rst mentioned contact portion; said shank portion comprising parallel sections of said strip, at least one of said shank sections being provided with a longitudinally extending stiiening rib.

9. A two-ply spring blade for electrical plug connectors and the like, comprising a. fiat, metal strip of uniform width which is folded upon itself at the outer end of said blade and shaped to provide'two, longitudinally spaced. two-ply, resilient contact 'portions and a shank portion, one of said contact portions being located at the outer end of said blade and comprising 'coextensive, substantially parallel sections of said strip which are spaced a. short distance from each other, the other of said contact portions being located longitudinally adjacent said ilrst-mentioned contact portion and comprising co-extensive sections of said strip which are spaced apart a substantially greater distance than said parallel sections, whereby said other contact portion has a substantially greater, maximum transverse width than said first-mentioned contact portion, and said shank portion comprising parallel sections of said strip which are fastened together by means 'which comprises an integral, formed part of one of said parallel sections.

10. A two-ply, spring blade for electrical plug connectors and the like, comprising a flat, metal strip of uniform width which is folded upon itself at the outer end of said blade and shaped to provide two, longitudinallyfspaced, two-ply, resilient contact portions and a shank portion, one of said contact portions being located at the outer end of said blade and comprising co-extens'ive, substantially parallel sections of said strip which are spaced a short distance from each other, the other of said contact portions being located longitudinally adjacent said first-mentioned contact portion and comprising co-extensive sections of said strip, at least one of which is outwardly bowed so as to cause said other contact portion to have a substantially greater maximum, transverse width than said first-mentioned contact portion, said shank portion comprising parallel sections of ysaid strip, which are in contact with each other and which are fastened together by means which comprises an integral, formed part of one ofsaid parallel sections, said contact portions and said shank portions being in substantially straight line alignment with each other. HUGO H. WERMINE.

REFERENCES CITED The following references are of record in the file of this patent:

Switzerland Nov. 1, 1935 

